gcc/c-family/
* c.opt (-Wdate-time): New option
* c-opts.c (sanitize_cpp_opts): Pass on to libcpp.
gcc/
* doc/invoke.texi (-Wdate-time): Document.
gcc/fortran
* lang.opt (-Wdate-time): New option
* cpp.c (gfc_cpp_option_data): Add warn_date_time.
(gfc_cpp_init_options, gfc_cpp_handle_option,
gfc_cpp_post_options): Handle it and pass on to libcpp.